Electron discharge tube



w. E. KUHLE ET AL ELEcTRoN DISCHARGE TUBE Filed oct. 17, 1954 Dec. 17, 1935.

)SDD )DE WILHELM EBERHARD KUHLE h lCH PRINZ ETELV HERRIGER NVENTORS @WZ/wf TTONEY Patented Dec. 17j, 1.935

UNITED STATES l 2,024,695 PATENT OFFICE ELECTRON DISCHARGE TUBE Wilhelm Eberhard Khle, Dietrich Prinz, and Felix Herriger, Berlin, Germany, assignors to Telefunken Gesellschaft fr Drahtlose Telegraphe m. b. H., Berlin, Germany, a corporation of Germany Application October 17, 1934, Serial No. 748,614 ln Germany October 7, 1933 2 Claims.

invention to provide an improved type of elec tron discharge tube of this character.

In the preferred embodiment of our invention the envelope of the tube consists of a hollow ceramic body, preferably cup-shaped, having a wall provided With a duct for circulating a cooling medium and wholly or partially metallized on the inside. In contrast with tubes having glass bulbs or envelopes, a tube made in accordance with our invention possesses greater heat stability and mechanical strength.

The novel features which we believe to be characteristic of our invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a longitudinal cross section of electron discharge tube made in accordance with our invention, and Figure 2 is a longitudinal cross section of a modification of an electron discharge device made in accordance with our invention.

In Figure 1 the electron discharge tube includes a ceramic cup or envelope I0 which has on its inside wall a metallic coating or lining II constituting the anode or plate. For the purpose of cooling the ceramic envelope I0 there is in the wall a helical duct I2 thru which water or other cooling medium can be circulated. The ceramic envelope II) is preferably-sld, shaped in longitudinal section, thus providing an external recess or cavity at its lower end into which the exhaust tube I3 extends thru the bottom or transverse wall I4 of the envelope. This arrangement protects the exhaust tube against accidental contact. The longitudinal wall of the envelope extending beyond the transverse wall increases the length of the cooling path so that the electrical resistance of the water column in the duct I2 is increased over what it would otherwise be. This is desirable since it tends to decrease the possibility of a break-down between plate or anode and ground by way of the duct. The exhaust tube I3 may consist of glass or of metal; and if of metal, can serve at the same time as the plate supply lead. In order to increase the protection against mechanical damage, it may be advantageous to surround tube I3 with a castable compound mass I5. The supply leads of the rilamentary cathode I6 and of the grid I1 are embedded in and extend thru a flat circular press I8 at the upper end of the ceramic envelope Ill. The press I8 is preferably made of glass to fa- (Cl. Z-27.5)

cilitate repairs. The outside wall of the ceramic envelope may be provided with metallic coverings I9 to provide a circuit element such as a condenser or a coil for an oscillating circuit in-which the tube might be used.

In the modification shown in Figure 2 the leadin conductors 20 and 2| to the grid 22 and the cathode 23 may be embedded in a flat circularv press 24 which is secured to the ceramic envelope 25 by means of a short intermediate glass tube 26. If the cathode 23 has to be replaced or renewed all that has to be done is to cut the glass tube 26 in two, replace the filament, and then restore the tube 26 by welding the two parts together. Metallic coverings 2l serve the same purpose as the metallic coverings I9 shown in Figure l.

While we have indicated the preferred embodiments of our invention of which we are now aware and have also indicated only one specific application for which our invention may be employed, it will be apparent that our invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of our invention as vset forth in the appended claims.

1. An electron discharge tube having a tubular 30 ceramic envelope, a press closing one end of said tubular envelope, a metallic coating on the interior wall of said envelope providing an anode, electrodes supported by said press within the envelope, a transverse wall closing the other end of the envelope, the longitudinal wall of the envelope extending beyond said tranverse wall and provided with a duct thru which a cooling Inedium may be circulated.

2. An electron discharge tube having a tubular ceramic envelope, a flat circular press closing one end of said envelope, a metallic coating on the interior wall of said envelope providing an anode, electrodes supported by said press within the envelope, a transverse wall closing the other end of the envelope, the longitudinal wall of the envelope extending beyond said transverse wall, said longitudinal wall being provided with a duct for circulating a cooling medium to cool the longitudinal walls of said envelope, and a metal ex- 

